Measuring devices known from industry such as electrochemical sensors or the like are used, for example, for determining a pH value of a liquid medium or even for determining a carbon dioxide component of a medium. Measuring devices designed for such purposes include potentiometric electrode pairs which may be constructed in different ways.
German Patent Application No. 44 24 213, German Published Patent Application No. 195 15 065, and German Published Patent Application No. 298 00 998 describe potentiometric sensors whose operation is based on the long-known principle that an electric voltage, which changes with the change in a chemical species concentration, is measurable between at least two electrodes. The electric voltage to be measured is induced by an electric potential difference resulting from a difference in the chemical equilibrium potential of the individual electrodes with their environment. This voltage is determined using the sensors known from the above-mentioned related art, which are designed using a pH-sensitive glass electrode as the working electrode and a reference electrode.
In chemical and pharmaceutical research, when investigating processes and also certain materials, high throughput development is performed, in which a plurality of syntheses may be performed in a known manner in parallel reactors under different process conditions in a cost-effective manner within a short period of time, and may be evaluated automatically. The use of a larger number of parallel reactors is, however, at the same time associated with a high degree of measurement complexity and with a number of the above-mentioned electrode pairs which is at least equal to the number of parallel reactors, in order to be able to monitor all parallel reactors simultaneously. At least one electrode pair is associated with each of the parallel reactors for reaction checking and reaction tracking.
Due to the large number of measuring points in the high throughput development, the equipment costs for process checking and process tracking are disadvantageously high, and the large space required by the electrode pairs in the area of the parallel reactors results in the parallel reactors having large dimensions. In order to reduce the equipment costs, there is always the possibility of limiting the number of glass electrodes and measuring the individual parallel reactors sequentially, for example.
This procedure, however, does not provide continuous tracking of the processes in the parallel reactors, which reduces the time advantage of the high throughput development. In addition, the glass electrodes must be cleaned when changing from one parallel reactor to the next one, which makes handling of such a system disadvantageously difficult.